Pusher assembly with dynamic width adjustment for stacker

Abstract

A pusher assembly for a stacker includes first and second opposing moving sidewalls, each sidewall defining a lateral side of a chute region, the chute region defining a centerline therethrough. A first pusher is located on the first sidewall and is movable therewith and a second pusher is located on the second sidewall and is movable therewith. The first and second pushers, when in a home position, are staggered from one another relative to the centerline. The first pusher engages a leading edge of a stack of material in the stacker and the second pusher engages a trailing edge of the stack. In a conveying position, the first sidewall moves to engage the first pusher with the trailing edge of the stack of material, and the first and second sidewalls both move in a forward direction to discharge the stack of material.

What is claimed is: 
     
       1. A pusher assembly for a stacker, comprising:
 first and second opposing moving sidewalls, each sidewall defining a lateral side of a chute region and each sidewall extending continuously to a first height defining a height of the chute region, the chute region defining a centerline therethrough, each sidewall reciprocally movable parallel to the centerline and transverse to the centerline; 
 a first pusher located on the first sidewall and movable therewith; 
 a second pusher located on the second sidewall and movable therewith, 
 wherein the first and second pushers, when in a home position, are staggered from one another relative to the centerline, the first pusher engaged with a leading edge of a stack of material in the stacker and the second pusher engaged with a trailing edge of the stack of material in the stacker, 
 wherein in a conveying position, the first sidewall first moves independently of the second sidewall to engage the first pusher with the trailing edge of the stack of material, and then the first and second sidewalls both move in a forward direction such that the first and second pushers discharge the stack of material from the chute region, 
 wherein the first and second sidewalls are configured to selectively engage and disengage the stack of material along a height of the stack of material in response to movement toward and away from the centerline, 
 wherein the first pusher includes (a) and (b) first pushers located on the first sidewall diametrically opposed to one another and the second pusher includes (a) and (b) second pushers located on the second sidewall diametrically opposed to one another, 
 wherein in the home position, the (a) first pusher is engaged with the leading edge of the stack of material and the (a) second pusher is engaged with the trailing edge of the stack of material, and wherein in the conveying position, the first sidewall moves to engage the (b) first pusher with the trailing edge of the stack of material, the (a) second pusher and the (b) first pusher moving in the forward direction to discharge the stack of material from the chute region, 
 wherein after discharge of the stack of materials from the chute region, the (b) first pusher and (b) second pusher move to the home position, and 
 wherein the (b) first pusher moves in a reverse direction to move to the home position and the (b) second pusher moves in the forward direction to the home position. 
 
     
     
       2. The pusher assembly of  claim 1  including a drive associated with each of the sidewalls, the drives being operable independently of one another. 
     
     
       3. The pusher assembly of  claim 2  wherein the drive for the first sidewall is operable in the forward direction and the reverse direction. 
     
     
       4. The pusher assembly of  claim 3  wherein the drive for the second sidewall is operable in the forward and the reverse directions. 
     
     
       5. The pusher assembly of  claim 1  including a sensor configured to sense a location of the first pusher relative to the home position and a sensor configured to sense a position of the second pusher relative to the home position. 
     
     
       6. The pusher assembly of  claim 1  wherein the pusher assembly is mounted to a turntable. 
     
     
       7. A pusher assembly for a stacker, comprising:
 first and second opposing moving sidewalls, each sidewall defining a lateral side of a chute region and each sidewall extending continuously to a first height defining a height of the chute region, the chute region defining a centerline therethrough; 
 (a) and (b) first pushers rigidly secured to the first sidewall at a fixed distance along the first sidewall relative to one another and movable with the first sidewall, the (a) and (b) first pushers being positioned diametrically opposed to one another on the first sidewall; 
 (a) and (b) second pushers rigidly secured to the second sidewall at a fixed distance along the second sidewall relative to one another and movable with the second sidewall, the (a) and (b) second pushers being diametrically opposed to one another on the second sidewall; 
 wherein the (a) first pusher and the (a) second pusher, when in a home position, are staggered from one another relative to the centerline, the (a) first pusher engaged with a leading edge of a stack of material in the stacker and the (a) second pusher engaged with a trailing edge of the stack of material in the stacker, 
 wherein in a conveying position, the first sidewall first moves independently of the second sidewall to engage the (b) first pusher with the trailing edge of the stack of material, and then the first and second sidewalls both move in a forward direction such that the (b) first pusher and the (a) second pusher discharge the stack of material from the chute region, 
 wherein after discharge of the stack of materials from the chute, the (b) first pusher and the (b) second pusher move to the home position, and 
 wherein the (b) first pusher moves in a reverse direction to move to the home position and the (b) second pusher moves in the forward direction to the home position. 
 
     
     
       8. The pusher assembly of  claim 7  including a drive associated with each of the sidewalls, the drives being operable independently of one another, the drive for the first sidewall being operable in the forward direction and the reverse direction. 
     
     
       9. The pusher assembly of  claim 7  including a sensor configured to sense a location of the first pusher relative to the home position and a sensor configured to sense a position of the second pusher relative to the home position. 
     
     
       10. The pusher assembly of  claim 7  wherein the pusher assembly is mounted to a turntable. 
     
     
       11. A method for pushing a stack of material from a stacker comprising the steps of:
 positioning a first pusher at a leading edge of the stack of materials, along a first lateral side of the stack of materials at a home position such that only the first pusher is positioned at the leading edge of the stack of materials at the home position; 
 positioning a second pusher at a trailing edge of the stack of materials, along a second side of the stack of materials, opposite the first side of the stack of materials at the home position such that only the second pusher is positioned at the trailing edge of the stack of materials at the home position; 
 moving the first pusher, independently of the second pusher, into engagement with the trailing edge of the stack of materials on the first lateral side of the stack of materials to a conveyance position, 
 moving the first pusher and the second pusher to discharge the stack of materials from the stacker; 
 positioning the first pusher at the home position; and 
 positioning the second pusher at the home position, 
 wherein the first pusher includes (a) and (b) first pushers and the second pusher includes (a) and (b) second pushers, and wherein the step of positioning the first pusher at the leading edge of the stack of materials, along the first lateral side of the stack of materials at the home position, is positioning the (a) first pusher at the leading edge of the stack of materials, 
 wherein the step of positioning the second pusher at the trailing edge of the stack of materials, along the second side of the stack of materials, opposite the first side of the stack of materials at the home position, is positioning the (a) second pusher at the trailing edge of the stack of materials, 
 wherein the step of moving the first pusher into engagement with the trailing edge of the stack of materials on the first lateral side of the stack of materials to a conveyance position, is moving the (b) first pusher into engagement with the trailing edge of the stack of materials, 
 wherein the step of moving the first pusher and the second pusher to discharge the stack of materials from the stacker is moving the (b) first pusher and the (a) second pusher to discharge the stack of materials from the stacker, 
 wherein the step of positioning the first pusher at the home position is positioning the (b) first pusher, at the home position, 
 wherein the step of positioning the second pusher at the home position is positioning the (b) second pusher at the home position, 
 wherein the step of positioning of the (b) first pusher at the home position includes moving the (b) first pusher in a reverse direction, and 
 wherein the step of positioning of the (b) second pusher at the home position includes moving the (b) second pusher in a forward direction coincident with moving the (b) first pusher in the reverse direction. 
 
     
     
       12. The method of  claim 11  including sensing a location of the first and second pushers at the home position.